Romance with Side Couples

I'm looking for romance manga where there is more than one couple portrayed. That can be either through friends of the main character(s) who get into a relationship or a love triangle where the "losing" part then ends up with someone else or something else along these lines. Also I would like it if the side couple is more than just a plot device to develop the main characters.

I know there is the "multiple love stories" tag but it's really incomplete. No yaoi, yuri and smut please, ecchi is ok. Also no collections of one-shots or other manga where the different couples share no connection with each other. Thanks.

I can't think of anything except for Shinshi Doumei † it's shojo manga with some shonen-ai and shojo-ai content, but the mangaka never shows any homosexual kisses, if that helps. But it's a really good series, I normally don't like super girlie manga but this one has a serious edge to it that makes it a good read.

Ran to Haiiro no Sekai it's not your typical romance; one guy is hated by more than half of the readers; and some things may be pretty disturbing; but, well, try it. There is for now one side couple, and maybe more later, since it's a pretty young manga.

There's nickelodeon too: one-shots, but almost all related if you pay attention.

"In a world where most people would be crazy, then it would be normal to be crazy and crazy to be normal... but then again, if you were normal, then you would be crazy... isn't it crazy what a paradox a little craziness can create?"